title: Effects of histamine and antihistamines on the kinetics of carbon dioxide in the rat.
abstract: We have investigated the effects of chlorpheniramine (an H1 histamine inhibitor) and metiamide (an H2 inhibitor) on response to 14C pulse-labeling of carbon dioxide in the rat in the presence and absence of histamine. Neither chlorpheniramine nor metiamide alone had any effect upon the gastric venous/arterial ratio (VG/A) or the peripheral venous/arterial ratio (Vp/A). As in the case with no drug present, Vp/A rose with time following pulse-labeling to a value of 1.15-1.20. The presence of a preexisting steady-state infusion of histamine caused no changes in the ratios in the presence or absence of the inhibitors. The inhibitors did completely abolish the oscillations of both VG/A and Vp/A caused by initiation of histamine infusion coincident with the pulse-labeling. The results suggest that the histamine effects are largely mediated through H1 receptors.
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000097:blood; D002245:Carbon Dioxide / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002744:Chlorpheniramine / Q000494:pharmacology*; D006632:Histamine / Q000494:pharmacology*; D007700:Kinetics; D008785:Metiamide / Q000494:pharmacology*; D011865:Radioisotope Dilution Technique; D051381:Rats; D011919:Rats, Inbred Strains; D013890:Thiourea / Q000031:analogs & derivatives*
chemical_list: D001639:Bicarbonates; D002250:Carbon Radioisotopes; D002245:Carbon Dioxide; D008785:Metiamide; D002744:Chlorpheniramine; D006632:Histamine; D013890:Thiourea